Although the invention is particularly applicable to internal gear or gerotor type motors and will be described with particular reference thereto, it should be noted that the present invention has broader applications and may be employed with other types of hydraulic devices, including pumps, such as gerotor type pumps.
Hydraulic devices of the type to which this invention is applicable are normally comprised of a housing, a fluid cavity in the housing and a shaft extending into and rotatably supported in the housing. Conventional gerotors provide an internally toothed ring gear and an externally toothed pinion gear that are disposed in the cavity of the housing and rotate with the shaft in a bearing surface eccentric to the axis of the shaft to define a plurality of increasing to decreasing volume fluid chambers. Inlet and outlet ports are formed in the housing and communicate with these chambers. Normally, when functioning as a motor, the chambers increasing in volume communicate with an inlet port at relatively high hydraulic pressures while the chambers decreasing in volume communicate with an outlet port and are at relatively low hydraulic pressures.
The high hydraulic pressures that are utilized to power gerotors are also utilized to fill passageways and cavities of the hydraulic motor for lubricating the necessary portions of the shaft and any bearing utilized to rotatably support the shaft. Because these high pressures utilized to power gerotors often reach levels of 1000 psig, it is difficult to effectively seal the shaft to the housing without having some amount of hydraulic fluid travel pass the seals along the shaft. Thus, it would be desirable to provide a sealing arrangement that could reliably and effectively seal a shaft of a hydraulic motor when exposed to high hydraulic pressures commonly utilized in gerotor type motors.
In many applications, such as automobiles, any amount or type of fluid leaking from such a hydraulic motor or pump cannot be tolerated. Therefore, it would be desirable to provide a hydraulic motor of the gerotor type that provided a draining means for receiving any fluid that may pass by the sealing means for sealing the shaft with respect to the housing and direct such fluid to a fluid reservoir.
The problem of sealing the shaft with respect to the housing is enhanced when dynamic forces are applied to the various parts of the hydraulic motor. For example, the shaft of the hydraulic motor is commonly connected to a means for accomplishing work, such as a pulley, spline, gear, shaft, etc. When this occurs, the shaft realizes lateral forces, especially in the instance of a pulley. If the shaft is not properly supported to withstand the lateral loads of a pulley, the sealing means for sealing the shaft with respect to the housing may become displaced, thus, degrading the sealing engagement of the shaft relative to the housing. Lack of proper support to the shaft against lateral loads may also lead to degradation of the motor's performance and, ultimately, to the degradation and failure of the internal mechanisms of the hydraulic motor.
Therefore, it would be desirable to provide a hydraulic motor of the gerotor type that properly supports a shaft from lateral loads in order to properly maintain a sealing engagement with the shaft relative to the housing and ensure the proper performance and functioning of the internal mechanisms of the hydraulic motor.